The invention relates to a method and device for producing an optimized neck contour (9, 14) on preforms. The invention also relates to a device and to a method for producing a preform having the optimized geometry (9, 14) below the neck which is optimal for subsequent stretch blow moulding. Said geometry has, in particular, a significantly thinner wall thickness than the neck itself. Said preform can only be produced in the injection moulding tool, when according to the invention axial channels are used on said point or the vanes produce the thin points on the preform during the injection moulding process. The thin-walled geometry on the preform can also be produced outside of the mould during post-cooling by embossing. The preform is then removed in a cooled receiving sleeve and is cooled in the body by intensive contact cooling while no cooling contact is made as far as possible with the preform neck on account of the initial position of the embossing element. Due to the reheating of the neck, which is possible as a result, they can be mechanically deformed into a new geometry which is advantageous for the blow moulding process and thus their wall thickness can also be influenced. In the subsequent blow molding process, a preform having a thin-walled area below the neck has primarily the advantage that the plastic material which is distributed better in the bottle can result in considerable material savings and higher quality bottles.